[BRAN]

Wow, nice! Those are really rare pieces.
As you mentioned, I only removed my old leather handle and re-installed the wooden one. And that was tricky enough, as they hardly come of and the fitment of the wooden handle was sub-par. Lots of filling was necessary.
How about contacting the seller, he might have an idea what happened to the top piece and how it came of. Btw. mine is just standard plastic, yours is leather...i guess i need to upgrade that, too (once you know, how the disassemble it) ;-)
But honestly, I could image, that it might be possible to push it back a few mm and then it can be lifted up. Just a guess, if I look at those screws.